It has another important property, the
MaximumRowsOrColumns property. With that property, you define when a break occurs. A vertical
VariableSizedWrapGrid will break to a new column, either when the number of rows is reached that you have defined in the
MaximumRowsOrColumns property or when there is no more vertical space left in that column. In a horizontal
VariableSizedWrapGrid, the children are stacked in a row. It will break to a new row when the number of columns has reached the number you have defined in the
MaximumRowsOrColumns property or when where is no more horizontal space left.

Now you can see in the Designer the
VariableSizedWrapGrid has now only two columns. After the two columns are reached, it breaks to a new row.
All right, now let's look at the attached properties
RowSpan and
ColumnSpan.